Set a default error message in Axios Interceptor

[uier]

We can set a default error message Unknown error occurred :( in Axios Response Interceptor to avoid having tons of places writing something like this:

new-front-end/src/pages/course/[name]/announcements/new.vue

Lines 43 to 53 in c77be18

	} catch (error) {
	if (axios.isAxiosError(error) && error.response?.data?.message) {
	errorMsg.value = error.response.data.message;
	} else {
	errorMsg.value = "Unknown error occurred :(";
	}
	throw error;
	} finally {
	isLoading.value = false;
	}
	}